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SF Year 1 > Lecture 15 and 16 > Flashcards

Lecture 15 and 16 Flashcards

1
Q

____________ protein catalysts that increase the overall rate of reaction without being changed in the overall process

A

enzymes

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2
Q

Enzymes convert substrates (reactants) into ______________ and channel them into useful pathways

A

products
*they do not invent new reactions they just increase the rate of reaction

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3
Q

_______ catalyze oxidation reduction reactions such as the conversion of lactate into pyruvate

A

oxireductase

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4
Q

_________ catalyze transfer of C-, N-, or P- containing groups such as serine to glycine

A

Transferase

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5
Q

_______ catalyze cleavage of bonds by addition of water

A

hydrolase

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6
Q

_________ catalyze cleavage of CC, CS and certain CN bonds such as the conversion of pyruvate to acetaldehyde

A

Lyases

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7
Q

_____________ catalyzes rearrangement of optical or geometric isomers

A

isomerases

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8
Q

______________ catalyze formation of bonds between carbon and O, S, and N coupled to hydrolysis of high energy phosphates

A

Ligases

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9
Q

Naming Enzymes

A

Common names: Usually have “-ase” added to the name of the substrate of the reaction and a description of the
action performed with the name of some of the substrates. Example: Lactate dehydrogenase

Systematic names: Include the names of all substrates in the reaction catalyzed and the respective class name + “ase” Example: Lactate:NAD+ oxidoreductase

Trivial namesSome retain the original trivial name, which does not give a hint as to the substrate or action.
Examples: trypsin, pepsin

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10
Q

Synthase vs synthetase: which one requires atp

A

synthase no atp
synthetase: requires atp

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11
Q

Oxidase vs oxygenase which one incorportes O2

A

‣ Oxidase – uses O2 as acceptor without incorporating it
‣ Oxygenase – one or both O2 atoms are incorporated

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12
Q

Phosphatase vs phosphorylase

A

‣ Phosphatase – uses H2O to remove phospho group
‣ Phosphorylase - add a phosphate group uses Pi to break a bond and generate phosphorylated product

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13
Q

_______ inorganic substances that are required for or increase the rate of catalysis

A

cofactors
EX: Zn2+

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14
Q

__________ organic molecules that are required by certain enzymes to carry out catalysis

A

coenzymes
Ex: vitamin derivatives: NAD+, FAD, NADP+

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15
Q

_____________ enzyme + non protein component (active)

A

Haloenzyme

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16
Q

____________ enzyme without non protein component (inactive)

A

Apoenzyme

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17
Q

________ the property of an enzyme to have a high turnover rate. It is the number of substrate molecules converted to product per enzyme molecule per second

A

Efficiency

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18
Q

________ only one or few substances, only one type of chemical reactions, the set of enzymes present in a cell determines which reactions will occur in the cell

A

Specificity

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19
Q

How do enzymes work

A

Enzymes work by lowering the free energy of activation without affecting the energies of the reactants

*they do not change the equilibrium, they accelerate equilibrium

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20
Q

________ a quantitative measure of the energy transfers between chemical reactions

A

Free Energy

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21
Q

______ the energy difference between that of reactants and the high energy intermediate that occurs during the formation of the product

A

Energy Barrier

22
Q

__________ the difference in free energy between the reactant and T

A

Free Energy of activation Ea

23
Q

_________ creates a unique microenvironment, allows for greater concentration of the intermediates that can be converted to products

A

stabilization of transition state

24
Q

What is the difference between the lock and key model vs the induced fit model

A

Lock and key: enzymes active site is a rigid structure that perfectly matches the shape of specific substrate

Induced fit: proposes that the active site an enzyme can change shape slightly better to accommodate substrate upon binding making it more flexible

25
Q

_______the number of substrate molecules converted to product per unit of time expressed as mol/ min

A

Reaction velocity

26
Q

What are some factors that affect reaction velocity

A

-Temperature, PH, and Substrate Concentration

27
Q

In terms of enzymes why are high fevers life threatening

A

Denaturing enzymes

Temperature optimum is ~37°C
Denaturation begins at ~40-42°C

28
Q

In terms of enzymes what is metabolic acidosis or alkalosis and what is the danger of it

A

It is a clinically High or low PH

For human enzymes:
‣ pH optimum is dependent on the
enzyme localization
‣ It affects ionization of the active
site and enzyme integrity

29
Q

___________ bind to a different site on the molecule and change the enzymes activity

A

Allosteric regulators

30
Q

________ the study of enzyme reaction rates and the conditions which affect them

A

Enzyme kinetics

31
Q

————–: A model to describe how reaction
velocity varies with changes in the
substrate concentration at a given
enzyme concentration.

A

MICHAELIS MENTEN
[E] + [S] –> [ES] –> [E] + [P]

Assumptions
-[S] is much greater than [E]
-[ES] does not change with time: steady state mechanism
-There is no appreciable back reaction from product to substrate

*Remember that Enzyme concentration is constant

32
Q

What is Km?

A

The amount of substrate need to half maximal velocity 1/2Vmax

33
Q

In terms how affinity for an enzyme how does this relate to Km

A

Low Km higher affinity
High Km lower affinity

34
Q

____________: at high concentrations of a substrate [S]&raquo_space; Km, the reaction is constant and indepent of substrate concentration

A

Zero Order

35
Q

___________ at low contractions of substrate the reaction is proportional to substrate concentration

A

First order

36
Q

On a line weaver burk plot what are the X and Y intercepts

A

X intercept: -1/Km
Y intercept: 1/ Max

37
Q

‣ bind to sites other than the
active site non-covalently
‣ Can alter the affinity of the
enzyme for its substrate
(affect Km)
‣ Can alter the maximal
catalytic activity (affect
Vmax)
‣ Can alter both

A

Effectors

*alloseteric regulators

38
Q

What are the types of enzyme inhibitors

A

Irreversible (bind to E through covalent bonds) actively can not be recovered

Reversible Bind to E through non covalent bonds. Activity can be recovered. Actively can be recovered

39
Q

What are the two types of reversible inhibitors

A

Noncompetitive: I binds to different site than enzyme
Competitive: I competes with S for the active site

40
Q

___________ E converts I into a reactive form in its active site

A

Suicide inhibitor

41
Q

What is an example of an irreversible inhibitor

A

Lead poisoning PB binds to SH groups in protein like ferrochelatase

42
Q

What is an example reversible non competitive inhibitor

A

Allopurinol reduce the production of uric acid used for treatment of hyperuricemia (gout)

43
Q

What is an example of Competitive inhibitor

A

Statin drugs are structural anacondas of HMG coA that inhibit synthesis of cholesterol

44
Q

What does competitive inhibition do to Vmax and Km

A

Increased Km
No effect on Vmax

45
Q

What does noncompetitive inhibition do to Vmax and Km

A

No effect on Km
Decreased Vmax

46
Q

What are the two types of plasma enzymes

A

-Actively secreted
-not actively secreted (function intracellularly)

47
Q

When do not actively secreted enzyme levels increase

A

When there is tissue damage

48
Q

__________:
‣A dimer composed of two polypeptides,
called B and M subunits
‣Has three possible combinations:
-CK1 = BB, found only in brain
-CK2 = MB, found only in heart
-CK3 = MM, found in skeletal muscle and
heart‣A dimer composed of two polypeptides,
called B and M subunits
‣Has three possible combinations:
-CK1 = BB, found only in brain
-CK2 = MB, found only in heart
-CK3 = MM, found in skeletal muscle and
heart

A

Creatine Kinase

49
Q

What happens to Creatine Kinase in a MI

A

Myocardial infarction (MI); specificity CK2 isoenzyme in the plasma is specific for MI appears 4-8 hours after MI, peaks at 24 hours, returns to baseline at 72 hours

50
Q

________ more predictive of adverse outcomes in MI than CK2, it is released into the plasma when cardiac tissue is damaged. It is highly sensitive and specific for cardiac damage. It appears 4-6 hours after, peaks at 8-28, and remains elevated for 3-10 days

A

Cardiac Troponin and Troponin I

SF Year 1 (20 decks)

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